The Prevalence of Onodi Cells and Analysis of Relationship With Optic Nerve in Koreans

Background and Objectives It is important to identify variations of paranasal sinuses during sinus surgery. The Onodi cell (OC), a variant of the paranasal sinuses, is the most posterior ethmoid cell with a close relationship with the optic nerve (ON). The purpose of this study is to evaluate the prevalence of OCs and analyze the relationship of OCs with ON in Koreans.Subjects and Method This retrospective study utilized CT images of 526 slides from 263 Korean adults. The prevalence of the OCs and the degree of indentation of the ON within the OC was determined using binary logistic regression analysis.Results The OCs were observed in 37.3% of 263 subjects and in 27.6% of 526 slides. The OCs are found more frequently in males than in females (p=0.01), and also more frequently in the right side than in the left side (p=0.001). Binary logistic regression analysis revealed that the ON protrusion in female was 0.339 times lower than in male and 1.052 times higher with the increased age. The ON protrusion within the OC in the postsellar type was 10.214 times higher than that in the presellar.Conclusion The OCs were observed in 37.3% of the Koreans. The protrusion of the ON within the OCs increased in male and in the postsellar type of the sphenoid sinus.